A non-reactive hot melt adhesive of the type mentioned in the opening paragraph is known as such. For example, the publication “Lactic acid based polymers as hot melt adhesives for packaging applications”, published in Int. J. of Adhesion & Adhesives 22 (2002), pages 219-226 describes such adhesive. More particularly, this document pertains to an investigation of copolymers based on poly(L-lactide) and poly(ε-caprolactone) with a molar ratio (L/C) of 81/19. Copolymers of this type are of interest because of their biodegradability. In compost environments it is apposite that the major part of the packaging material can be degraded within a certain period of time. It is therefore important that possible remaining adhesive material can also be degraded within the same period of time.
The known non-reactive hot melt adhesive shows an important disadvantage. It has appeared that its long term thermal stability is not optimal. Thus, the adhesive properties appear to degrade in an unacceptable manner if the adhesive is exposed for a long period of time to a higher temperature. Unwanted effects like loss of adhesion strength are observed, especially if the adhesive is stored for several days or more at temperatures of approximately 175° C. or more. After such exposure period, it cannot be used properly for sealing packages, especially if the material of the package is composed of cardboard, wood and other types of packaging materials.